How to De-Winterize a Boiler

Visually inspect all water supply pipes and repair any that appear to have burst, corroded, cracked or leaked in any way.

Turn off electrical supply to the boiler if it is electric.

Inspect and clean or replace, if necessary, any drains or traps that receive water flow.

Attach a garden hose to the top of your boiler and to the source of water you will use to fill it, such as a laundry supply faucet.

Ensure all faucets inside the building and outside are off. If any remain open, close them. These lines, which include outside hose faucets, were probably fully opened to drain all the remaining water during the process of winterization.

Turn the shutoff valve, which resembles a faucet, to the closed position on the bottom of the boiler. Turn the manual lever on the pressure and temperature relief valve, usually indicated with a red colored handle and often indicated with the words "pressure relief" or "relief valve," to the off position. Shutting these valves off will ensure that the water you add to the boiler won't leak out from the bottom faucet when you refill the heater with water.

Open a single faucet that is outside the building. This will help to confirm that the water supply is working once the main line is opened, and also bleeds air and water out to relieve sudden water pressure fluctuations that can cause water to spray.

Open the boiler-feed faucet that is fed water from a garden hose and is usually located at the top of the boiler. Open the main water supply control that is found outside the building, attached to your water meter. Check the outside water faucet you opened to ensure water is flowing. If you don't have a shutoff water valve on the boiler, the water will immediately begin to fill the boiler. If you have a shutoff valve, open it slowly to allow water to begin filling the tank.

Turn off the faucet connected to the garden hose that feeds into the boiler, once the boiler is full.

Check for water leaks. Repair any leaking areas.

Gradually turn on the gas flow to the boiler if applicable.

Light the boiler if you have a gas heater, or turn on the electric circuit.